I used this during my engine assembly, and now Im having second thoughts. They say that it is good for oil, coolant, gasoline, LPG, etc, but I used it to seal the NPT fittings on my fuel rails and regulator, and it didn't work at all. Every joint leaked profusely. I replaced it with some proven sealer from Hercules, and now the fuel rails are sealed and all is well, but I also used the ARP stuff to seal my head bolts. Has anyone used it with success on cooling systems? Im hoping it was just from the fact that the base used is soluble in gas.

 

I sealed up my fuel lines with it... I haven't hjad any problems.

 

Was that on a low pressure system like TBI? I tested it at 45 PSI, and all the fittings leaked, even the 1/8" NPT fittings. It seemed to be an issue with the base being washed away by the fuel. The other stuff I used works great. I just hope I dont have 34 coolant leaks when I go to start the motor for the first time.

 

Actually it's just a carb system... so you're probably right on that. Just 5 psi or so.

 

It's just pipe dope. There's nothing special or exotic about it.
Use it on NPT connections ONLY. And yes, it'll be fine to about 2000psi - IT'S PIPE DOPE. The threads do the sealing anyway. If an NPT seal leaked, you didn't tighten it hard enough.
It'll be fine on your head bolts. You just put a bit on the threads to seal into the block eh?

 

I used the sealant on the threads and under the heads/washers. Same procedure I did last time, except I used the 'real-tuff' from hercules, which seals very well. When I took the old heads off, the bolts where dry after around 5 years of use.

The fittings where about as tight as I dared make them, and they still leaked with the ARP stuff. Evey fitting leaked, even the fine thread 1/8 NPT fittings, which normally do seal themselves. I reassembled with the other sealant, and they all sealed fine. I probably should have just stuck to what worked rather than use the ARP junk. Probably end up having to pull the head bolts one at a time to reseal. Just get the feeling that it'll leak.

 

I did a quick search, and some people swear by the ARP stuff. I hope it works. I REALLY dont want to have to tear it back down. With the SFI setup, disassembly is a real bitch.